The present invention relates generally to mobile robots and more particularly to robots capable of climbing and traversing horizontal, angled and vertical surfaces, including making transitions between the two. Such robots are used for remote inspection of bridges, aircraft, and other man-made structures.
There are two basic types of robots used in commercial applications today. The first, and most prevalent, is the industrial robot which, while confined to a relatively fixed position, employs various linear, rotary, and other actuators and effectors to position a limb for manipulating or performing work on an object, such as in a manufacturing assembly line. A second type of robot is the mobile robot which can propel itself to different locations, allowing it to perform remote sensing and inspection tasks on man-made structures, such as bridges, buildings, and aircraft. Some mobile robots are also used to deliver light payloads to almost any point on a structure.
Most mobile robots found in the prior art are limited to rolling or walking across a floor, on a flat surface. Some prior art mobile robots have been provided with climbing feet, giving the robot the capability of moving along a non-horizontal surface or, in some cases, enabling it to step over objects which may otherwise interfere with the path of the robot. For example, U.S. Pat. No. 4,674,949 discloses a robot having climbing feet, allowing it to move along a non-horizontal surface. Movement is effected by translation of a motorized slide while suction cups hold the robot in place and jacks elevate the slide. However, the movement described by the inventor of the '949 device would be virtually impossible if any reasonably sized object intervened.
In U.S. Pat. No. 4,977,971, a mobile robot is described in which four tracked "legs" are attached to a central body through multiple joints which allow the feet to pivot, tilt, and lift in three distinct movement modes. The '971 robot apparently can climb stairs and maneuver around obstacles but does not appear capable of climbing vertically or making an effective transition from, for example, floor to wall.
The four sided scaling robot described in U.S. Pat. No. 5,077,510 is a frame device which can climb vertical surfaces using suction cups. A single linear actuator produces movement. However, it does not appear that the '510 device can step over obstacles nor make an easy transition from horizontal to vertical travel.
Prior art wall climbing robots have typically been provided with linear screw actuators which produce leg extensions/contraction, a sideways motion, or leg rotation movements, to allow transition of the robot from a horizontal to vertical movement surface. The use of such actuators and motion results in a mobile robot which is heavy and unwieldy, thereby restricting its useful application.
What is needed, then, is a compact mobile robot which has multiple degrees of freedom of movement, which can move horizontally, climb vertical surfaces, and traverse obstacles, is relatively simple in its design and construction, and is both high in strength and low in weight. Such a robot is presently lacking in the prior art.